Method for brazing of titanium and aluminium parts and parts obtainable thereby

Abstract

Aluminium and titanium parts can be joined to each other by brazing in the presence of an alkali metal fluoroaluminate in a protective gas atmosphere which comprises argon. According to the process, the assemblies of aluminium and titanium, joint by brazing, can be used for example in or as chemical apparatus, as parts for cars, boats, space transportation systems, or airplanes, or for manufacturing heat exchangers.

1 . A method for brazing of titanium with aluminium in the presence of a flux based on alkali metal fluoroaluminate and in the presence of a protective gas containing equal to or more than 75% by volume of a gas selected from the group consisting of helium, argon, xenon, and any combinations thereof, or under a vacuum. 
     
     
         2 . The method according to  claim 1  wherein the alkali metal fluoroaluminate is potassium fluoroaluminate, cesium fluoroaluminate, or a mixture of both. 
     
     
         3 . The method according to  claim 2  wherein the flux comprises potassium fluoroaluminate and cesium fluoroaluminate, wherein equal to or more than 0.1% by weight and equal to or less than 10% by weight of cesium fluoroaluminate, relative to the total fluoroaluminate flux content set to 100% by weight, is comprised. 
     
     
         4 . The method according to  claim 1  wherein the alkali metal fluoroaluminate is applied as dry flux, in the form of a flux composition with an organic solvent, in the form of an aqueous flux composition, or in the form of a paste. 
     
     
         5 . The method according to  claim 4  wherein the aqueous flux composition, the flux composition with an organic solvent or the paste comprises an additive, selected from the group consisting of a binder, a thickener, a thixotropic agent, a solder metal, and/or a solder metal alloy, and any combinations thereof. 
     
     
         6 . The method according to  claim 1  wherein brazing is performed in the presence of a protective gas containing equal to or more than 75% by volume of a gas selected frongItheotr helium, argon, xenon, and any combinations thereof. 
     
     
         7 . The method according to  claim 6  wherein brazing is performed in the presence of a protective gas containing equal to or more than 75% by volume of argon gas. 
     
     
         8 . The method according  claim 1  wherein brazing is performed at a temperature equal to or higher than 550° C., and at a temperature equal to or lower than 680° C. 
     
     
         9 . The method according to  claim 8  wherein brazing is performed at a temperature equal to or higher than 570° C., and at a temperature equal to or lower than 630° C. 
     
     
         10 . The method according to  claim 1  wherein the flux comprises a mixture of potassium tetrafluoroaluminate and dipotassium pentafluoroaluminate and/or their hydrates. 
     
     
         11 . The method according to  claim 1  wherein an aluminium-silicon alloy is applied as solder metal. 
     
     
         12 . Method The method according to  claim 1  wherein car parts, airplane parts, heat exchangers or apparatus for chemical reactions are produced. 
     
     
         13 . A brazed assembly comprising aluminium and titanium parts, obtainable by the method according to  claim 1 .